A fuel tank for use in a vehicle with a pump module provided inside to supply fuel to an engine with the pump module is disclosed in Japanese Patent Laid-Open Publication No. 2002-295327, for example. This fuel tank will be described with reference to FIG. 5.
As shown in FIG. 5, a pump module 100 for a fuel tank has a fuel pump 101 provided inside a chamber 102. The chamber 102 is supported on a lid member 105 via a sliding member 103 in a vertically movable manner. The lid member 105 closes an opening (hereinafter referred to as a tank opening) 104 in a tank body 106 with the chamber 102 disposed within the tank body 106. The chamber 102 within the tank body 106 is pressed onto the bottom of the tank body 106 by a spring member 108 of the sliding means 103.
With this pump module 100, the fuel pump 101 is driven to draw in fuel within the chamber 102 through a filter 110 to supply the indrawn fuel to an engine (not shown) through a supply pipe 112.
The tank body 106 generally changes in height due to changes in internal pressure, thermal expansion or the like. In order to constantly and adequately pump up fuel against the change, the pump module 100 has the sliding means 103 to move the chamber 102 up and down in response to changes in height of the tank body 106, thereby to constantly keep the chamber 102 at the bottom of the tank body 106.
The sliding means 103 includes a supporting rod 114 for supporting the chamber 102 vertically movably relative to the lid member 105. An upper end portion 114a of the supporting rod 114 is retained at the lid member 105. A compression spring 108 is provided on the supporting rod 114. A lower end portion 114b of the supporting rod 114 is slidably supported in a guide hole 116 in the chamber 102.
In the tank body 106 of a high height, the sliding means 103 presses the chamber 102 down with the compression spring 108 so as to keep the bottom 102a of the chamber 102 abutting the bottom of the tank body 106. On the other hand, in the tank body 106 of a low height, the chamber 102 is pressed up by the bottom of the tank body 106 against the compression spring 108. That is, the sliding means 103 is a position-adjusting means for the chamber 102 when the tank body 106 changes in height due to a change in internal pressure and thermal expansion.
In particular, the tank body 106 molded from resin has a relatively large amount of change in height due to a change in internal pressure, thermal expansion or the like.
In addition, automobiles have been diversified in form in recent years, and there is the need to prepare thin fuel tanks of low heights, for example, to meet the diversification.
Since the thin fuel tanks are smaller in the height dimension of the tank body 106 than regular fuel tanks, it is necessary to increase the tank width or the tank length to store as much fuel as regular fuel tanks. However, an increase in the tank width or the tank length of a fuel tank results in an increase in fuel level change due to inclination of the fuel tank. Therefore, in order to stably supply fuel to an engine, it is necessary to increase the volume of the chamber 102 to store sufficient fuel in the chamber 102.
In order to ensure a sufficient volume of the chamber 102, it is necessary to increase the outside diameter of the chamber 102 to make it almost agree with the inside diameter of the tank opening 104. This is because if the outside diameter of the chamber 102 is made greater than the diameter of the tank opening 104, the chamber 102 cannot be put into the tank body 106 through the tank opening 104.
The pump module 100 has an inner tubular portion 105b protruded downward from a plate 105a of the lid member 105 to seal the space between the tank opening 104 and the lid member 105 when the tank opening 104 is closed by the lid member 105.
In order to seal the tank opening 104 and the inner tubular portion 105b, it is necessary to make the outside diameter of the inner tubular portion 105 almost agree with the inside diameter of the tank opening 104. The inner tubular portion 105b is disposed opposite to an upper end portion 102b of the chamber 102.
Since a thin fuel tank is small in the height dimension of the tank body 106, when the height of the tank body 106 changes due to a change in internal pressure, thermal expansion or the like, the ratio of the change to the tank height is increased. Therefore, it is necessary for the pump module 100 fitted in a thin fuel tank to ensure a large amount of raise of the chamber 102.
However, since a thin fuel tank is lower in height than a regular fuel tank, the space between the upper end portion 102b of the chamber 102 and the inner tubular portion 105b of the lid member 105 is narrow. Therefore, when the height of the tank body 106 changes due to a change in internal pressure or thermal expansion, the chamber 102 being largely raised causes the upper end portion 102b of the chamber 102 to abut on the inner tubular portion 105b, preventing the raising of the chamber 102 midway. Therefore, the conventional pump module 100 cannot be applied to a thin fuel tank. Thus, there is demand for development of a pump module for fuel tanks applicable to thin fuel tanks.